Sonic techniques and apparatus for earth boring



some TECHNIQUES AND APPARATUS FOR EARTH BORING Filed Feb. 23, 1965 Dec. 13, 1966 A. G. BODINE, JR

2 Sheets-Sheet 1.

INVENTOR. ALBERT G. BODINE, JR.

fa; Q/wm/ we ATTORNEY Dec. 13, 1966 A. GLBODINE, JR 3,291,228

SONIC TECHNIQUES AND APPARATUS FOR EARTH BORING 2 Sheets-Sheet F3 Filed Feb. 25, 1965 FIG. 6

FIG. 6b

INVENTOR.

M m U w M T/ mm 2% A FIG. 5

United States Patent 3,291,228 SUNlfiC TECHNIQUES AND APPARATUS FOR EARTH BQRING Albert G. Bodine, Jr., 7877 Woodley Ava, Van Nuys, Calif. Filed Feb. 23, 1965. Ser. No. 434,423 14 Claims. (Cl. 175--55) This application is a continuation in part of my copending application Ser. No. 34,805, filed June 8, 1960, now Patent No. 3,211,243. This invention relates to sonto techn ques and apparatus for earth boring, and more particularly to such techniques and apparatus in which the boring tool is torsionally reverse turned while sonic energy is simultaneously applied thereto longitudinally at a frequency substantially higher than the reverse turning frequency.

in the aforementioned co-pending application, a particular method and apparatus for sonic drilling is described in which the drilling member is rotated continually in one direction while sonic energy is simultaneously applied thereto. The frequency of the vibration energy is such as to set up longitudinal elastic standing Wave vibration in the drilling shaft and on the drill itself. As eX- plained in said aforementioned pending application and my Patent No. 2,554,005, the high velocity vibration set up in the drill bit cause the formation being drilled to be set into a substantial degree of elastic vibration. The formation being dr'lled is thereby caused to rapidly fatigue and fracture. and in this manner the drlll'ng operation is greatly facilitated.

With the technique and apparatus principally described in the aforementioned pending application Ser. No. 34,805, the drill is continuously rotated in one direction. This technique is therefore not suitable for utilization with apparatus wherein the drill rod is suspended from a cable because of the windup of such cable that would result from such continual unidirectional rotation. With the device and method of this invention, the drill is turned first in one direction and then in the opposite direction at a different frequency than that of the longitudinally applied sonic energy. The technique and apparatus of this invention by providing the necessary torsional action of the drill without any net turning of the drill rod enables the utilization of a cable suspension.

It has been found that the use of reverse turning in addition provides a number of other advantages over the unidirectionally rotating drill. First, a reverse torsional action on the earth formation subjects such formation to a unique stress pattern which has force vectors which more efiiciently fatigue the formation, thereby enhancing the drilling operation. In addition, the reverse rotat on more efficiently tends to periodically free the path of the sonic tool from larger rock cuttings. Still further, the opposite rotation of the drill bit against the earth formation tends to have a self-sharpening effect, thus increasing the life of the bit. It has also been found that the gross reversing of the torque tends to shift the combined stress patterns produced in the resonant rod by the combined effects of the sonic vibration and the rotation. This shifting tends to distribute the stresses so as to increase the fatigue life of the drill rod.

It is very important to note that this invention does not involve any vibrating pattern resulting from having the sonic action and the rotary oscillation ope-rating at the ice same frequency. Any such single frequency for the two cyclic motions necessary gives a resulting script pattern of bit tooth motion which is undesirable where this invention is practiced, specifically in abrasive rock formation where script, Lissajous, or closed figure motion tends to dull the bit from sl'dng motion that is involved. With this invention the bit tooth is only conscious of longitudinal sonic drive while it is simply turning in a sustained rotary motion for an appreciable time interval. The time intervals are repeated in reversed direction.

This invention, then, is a combination of a longitudinal sonic resonant drilling system with rotary turning of the bit while the longitudinal action is taking place. The important novel feature here is that this torsional motion is a rotary turning in a single direction during a number of cycles, in excess of one cycle, of the longitudinal sonic action. As far as the bit is concerned, then, it is experiencing rotary turning during the time it is going through the longitudinal action. It i important to note that this is not a combination of rotary and longitudinal action at the same frequency, wherein the bit describes a Lissajous Wave pattern. On the other hand, this is simply a turning process.

It is therefore an object of this invention to provide an improved technique and apparatus for rotary sonic drilling.

It is a further object of this invention to enable the utilization of a cable suspension in a son'c rotary drill.

It is still a further object of this invention to provide a technique and apparatus for providing more efficient combined longitudinal sonic and rotary drilling action.

It is still another object of this invention to provide a sonic rotary driil less subject to wear and fatigue than similar prior art devices.

Other objects of this invention will become apparent from the following description taken in connection with the accompanying drawings, of which FIG. 1 is a plan View illustrating the overall drilling mechanism in which the device of the invention may be incorporated,

FIG, 2 is a cross-sectional view illustrating a motor drive mechanism that may be utilized in the device of the invention,

FIG. 3 is a cross-sectional view illustrating an oscillator mechanism for generating longitudinal vibrations that may be utilized in the device of the invention,

FIG. 4 is a cross-sectional view of a first embodiment of a torsional drive mechanism that may be utilized in the device of the invention,

FIG. 5 is a cross-sectional view of a second embodiment of a torsional drive mechanism that may be utilized in the device of the invention shown in conjunction with an associated oscillator mechanism for generating longitudinal vibrations,

FIG. 6 is a cross-sectional view taken along the plane indicated by 5-5 in FIG. 5, and

FIGS. 6a and 6b are schematic drawings illustrating the generation of the torsional oscillation in the embodiment of FIG. 5.

In analyzing the performance of a mechanically vibrating system, it is most helpful to analogize such a system to an electrical circuit. This type of dynamic analogy is Well known in the art and is described, for example, in Chapter 2 of Sonics, by I-lueter and Bolt, published by John Wiley and Sons in 1955. Thus, the

effective compliance C of the mechanical circuit is analogized to the capacitance in an electrical circuit; effective mass M in the mechanical circuit is analogized to inductance in the electrical circuit; mechanical resistance R in the mechanical circuit is analogized to electrical resistance in the electrical circuit; and vibrational velocity u in the mechanical vibrational circuit is analogized to electrical current in the electrical circuit. If the mechanical circuit is driven by a sinusoidal force F sin wt, then the differential force equation for the mechanical circuit is as follows:

1 du fudt+R u+M (1) This is, of course, completely analogous to the voltage equation in a similar electrical circuit, voltage being analogous to force.

It also can be shown that the mechanical impedance Z of a mechanical circuit, which is equivalent to electrical impedance, can be described as follows:

F sin wi= 1 F sin wt mom) u where w is the angular velocity of the drive signal which is equal to 211- times the frequency of such sinusoidal signal.

It can be seen from Equation 2 that velocity of vibration a varies inversely as a function of impedance Z Thus, high velocity is obtained where impedance is low and vice versa. Just as in an equivalent electrical circuit, energy is most efiiciently transmitted through matched impedance elements and where a mismatch occurs a high reflected wave results. This manifests itself by high relative movement at an interface between mismatched elements. Such a mismatch condition, as to be shown, is used to advantage in the device and technique of this invention.

A resonant condition is reached where wM is equal to I/wC in which situation it can be seen from inspection of Equation 2 that wM and l/oC cancel each other out, leaving impedance Z equal to resistance R Under such resonant conditions it can further be seen from Equation 2 that velocity of vibration u is maximum for any given mechanical circuit. It is also to be noted that at resonance, the power factor of the circuit is unity with force F being in phase with displacement velocity u. Therefore, the employment of a resonant vibrating circuit to apply energy from an oscillator to an earthen formation to be penetrated provides optimum utilization of the energy at hand.

It is further to be noted'that as the sharpness of resonance of an electrical circuit is determined by the Q thereof (indicative of the ratio of energy stored to the energy used in each cycle) so also the Q of a mechanical resonant circuit has the same significance and is equal to the ratio between wM and wR Thus, a high Q resonantly vibrating system is capable of producing considerable cyclic motion. In view of the fact that the acceleration of a sinusoidally vibrating mass is a function of the square of the frequency of vibration thereof, very high accelerations and thus forces can be developed even at moderately high resonant vibration frequencies.

The principles set forth above provide equally well to both longitudinally and torsionally vibrating systems.

It should be kept in mind that the various qualities such as mass, compliance and resistance are seldornly lumped in a physical embodiment of a mechanical circuit but are rather distributed throughout the components thereof with most of such components exhibiting all three member 14 proceeds through earthen formation 17. The drilling rig controlling cable 12 may be of conventional configuration, such as, for example, similar to that shown in my Patent No. 2,554,05. Rod 11 has mounted therein a mechanical oscillator unit 18 which mechanically vibrates the rod longitudinally at a resonant frequency so as to produce standing waves thereon, such standing waves being schematically illustrated by curved lines 19a and 19b.

The standing Waves are set up in rod 11 so that the anti-nodes of vibration velocity u, appear in the vicinity of oscillator 18 and at bit 14, with a half-wave standing wave pattern as shown in FIG. 1. Rod 11 can also be made to operate at multiples of halfwave resonance if so desired. In each instance, however, the velocity antinodes should appear in the vicinity of the oscillator and at bit 14 to assure optimum transfer of energy from the resonant rod to the earth formation in achieving the desired end results. Rod 11, in effect, operates as a resonant amplifier and transmission line in transmitting the output of the oscillator to the bit which has a similar high velocity vibration impedance characteristic.

Bit 14 is torsionally rotated first in one direction, then in the opposite direction, by means of torsional drive unit 20, operation of which is explained fully in connection with FIG. 3. For proper operation of the device of the invention, the frequency of the torsional oscillation of bit 14 is substantially lower than the resonant longitudinal vibration of rod 11, and bit 14 is typically rotated to and fro over an arc of between 5 and 30 degrees. Typical longitudinal vibration frequencies for rod 11 are between and 200 cycles per second, with typical torsional frequencies for bit 14 of between 5 and 20 cycles per second. Rod 11 is preferably fabricated of a material such as steel having qualities to make for a high Q resonant circuit with optimum vibration output.

With the simultaneous high velocity resonant vibration of rod 11 along its longitudinal axis and the to-and-fro torsional rotation of the bit 14, earth formation 17 is rapidly fatigued to provide highly efficient drilling action. The impedance mismatch between the high impedance earth formation and the lower impedance appearing at the bit makes for high relative movement which tends to enhance the fluidization of the soil. The advantages of the torsional reverse turning as compared with continuous unidirectional turning have already been thoroughly set forth earlier in this specification.

Referring now to FIGS. 2 and 3, a mechanical oscillator and its associated drive mechanism that may be utilized in the device of the invention for generating longitudinal vibrations is illustrated. A plurality of rotor units 25 are rotatably mounted on shafts 26. Rotors 25 each include eccentric weighted portions 30. Electric motor 37 is driven by power supplied through power lines 38. The output shaft 32 of electric motor 37 rotatably drives beveled gear 40. Gear 40 in turn drives gear 41 which is rotatably mounted on shaft 42. Also mounted on shaft 42 is gear 43 which rotatably drives the gear train including gears 44a-44d. Each of gears 44a44d is attached to a respective one of rotor units 25 and rotatably drives its associated unit on a respective shaft 26. Thus, with rotation of the gear train the rotor units associated with gears 44a and 440 are driven in one direction, and the rotor units associated with gears 44b and 44d are driven in the opposite direction. Rotors 25 are phased so that their weighted portions 30 are positioned as indicated in FIG. 3, so that the forces produced by such weights are additive along the longitudinal axis of rod member 11, and cancel each other out along lateral axes. Thus, a longitudinal oscillation at the frequency of rotation of rotor units 25 is generated.

This type of orbital mass oscillator is similar in configuration and operation to that described in my Patent No. 2,554,005, and produces a high force sonic vibration. This orbital mass oscillator has the unique characteristic of tending to lock in with the resonantly vibrating system, automatically adjusting its rotation frequency to changes in the load. In this way, optimum resonant operation is maintained at all times.

Gear 44d drives the speed reduction gear train, which includes gears 49-53. Gear 53, which is mounted for rotation on shaft 57, thus is rotatably driven at a considerably lower speed than gear 44d. Gear 58, which is mounted in shaft 57, thus rotatably drives gear 59 and its associated shaft 63% at a substantially lower rate than the rotation of the orbital mass oscillator rotors.

Referring now to FIG. 4, a first embodiment of a torsional oscillator which may be utilized in the device of the invention is illustrated. Fixedly attached to the end of shaft 60 is short crank arm 62. Fixedly attached to the bottom side of crank arm 62 and displaced axially from an extension of the longitudinal axis of shaft 60 is pin member 63. Bit drive shaft 66 is fixedly attached at one end thereof to bit 14 and is rotatably mounted on bearings 65. Fixedly attached to the other end of drive shaft 66 is long crank arm 68. Pin member 70 is fixedly attached to crank arm 68 and rotatably engaged in a bearing hole in connecting link 71. Pin member 63 is also rotatably engaged in a bearing hole formed in connecting link 71. Crank arms 62 and 68, operating in conjunction with connecting link 71, form a pitman or connecting rod linkage which effectively converts the unidirectional rotary motion of shaft 60 to reciprocating to and fro motion of shaft 66. In view of the stepped-down rotation of shaft 60 from the rotation frequency of oscillator unit 18, bit 14 is simultaneously longitudinally vibrated at a first frequency, and torsionally oscillated to and fro at a second substantially lower frequency.

Referring now to FIGS. 5 and 6, a second embodiment of a torsional drive mechanism operating in conjunction with a longitudinal vibration oscillator is illustrated. In this embodiment, the orbital mass oscillator and its associated resonant stem is torsionally driven as a unit by the torsional drive system.

Electric motor 75 which receives its power through cable 80 rotatably drives the gear train, including gears t-l183. Attached to gears 82 and 83 are rotor members 35 and 86 respectively. Rotors 85 and 86 are mounted in lubricant retaining casing 90 for rotation on their circumferential surfaces which form radial load bearings, and thrust bearings 91. Rotors 85 and 86 form a pair of orbital mass oscillators which are rotated in the same direction about axes parallel to the longitudinal axis of rod member 11. These rotors are positioned, however, so that their eccentric Weighted portions 95 and 96 are always 180 out of phase with each other. Thus, when weighted portions 95 and 96 are in the position indicated in FIG. 6 and in a position 180 removed therefrom, the weights produce equal and opposite forces which effectively cancel each other out. However, when the weights are in the positions indicated in FIGS. 6a and 6b, a torsional oscillatory couple is generated in the rotational directions indicated by the arrows in each figure. Thus, a torsional couple is produced twice during each rotational cycle of rotor units 85 and 86, such couple being oscillatory. This oscillatory rotational couple is transmitted to torsion tube 100. Torsion tube 100 is rotationally twisted alternately in opposite directions by the torsional force applied thereto. Torsion tube 100 is fabricated of a highly elastic material such as an elastic steel.

For optimum efficiency, it is desirable to form a torsional resonant system, such system including tube 100 and the components attached thereto including rod member 11 and bit 14. Such torsional resonant vibration can be achieved in the same general fashion as longitudinal vibration by proper choice of the torsional drive fre quency to match system component characteristics. Thus, by reference to Equation 2, it can be seen that if the effective torsional mass reactance seen by the torsional drive system can be made equal to the effective torsional compliant reactance, a resonant condition will be achieved with maximum torsional vibration velocity occurring at bit 14 with unity power factor and minimum force loss in the torsionally vibrating system itself. With components such as tors-i0 ntube 100 chonse for high Q characteristics, very high torsional outputs can be achieved from relatively low amounts of input power.

In a halfwave resonantly vibrating torsional system, the end of torsion tube adjacent to rotor units and 86 is rotated in one direction while the end of the torsion tube attached to stem 11 is rotated in an opposite direction about the effective center of the torsional system. Torsion tube thus acts like a transmission line in efficiently transmitting energy from the torsional oscillator to stem 11. I

Mounted within stem 11 is an orbital mass oscillator unit 18 similar in configuration and operation to that described in connection with FIG. 3. This orbital mass oscillator is driven by motor 37 which receives its power through the cable 80. Stem 11 and bit 14 are resonantly vibrated along the longitudinal axis of the stem in the same fashion as for the embodiment described in connection with FIG. 4. As for the embodiment of FIGS. 1-4, in the embodiment of FIG. 5, the torsional oscillation should be at a substantially different frequency than the longitudinal vibration to produce the desired end results.

It is to be noted that while a resonant torsional system generally will provide maximum efficiency, such resonance is not absolutely necessary to achieve reasonably satisfactory results. It is also to be noted that while in a halfwave resonant system the opposite ends of such system rotates simultaneously in opposite directions, such ends may rotate simultaneously in the same direction in other types of resonant systems.

The technique and device of the invention thus provide simple yet highly effective means for improving sonic drilling by combining to-andfro torsional rotation of the bit at a relatively low frequency, with higher frequency longitudinal vibration thereof. Such to-and-fro torsional vibration enables the utilization of a suspension cable by causing no net turning of such suspension, and further enhances the drilling action and minimizes fatigue of the drilling equipment.

While the method and device of the invention have been described and illustrated in detail, it is to be clearly understood that this is intended by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of this invention being limited only by the terms of the following claims.

I claim:

1. A method for earth boring by means of a drill bit attached to the end of a rod member comprising longitudinally vibrating said rod member and said bit at a sonic frequency,

while said rod is being longitudinally vibrated torsionally oscillating said bit to and fro at a substantially lower frequency than the longitudinal vibration and through at least a substantial fraction of a revolution in each rotational direction.

2. The method of claim 1 wherein said rod member and bit are vibrated resonantly.

3. The method of claim 2 wherein said bit is torsionally oscillated resonantly.

4. A device for boring through earthen formations comprising,

a rod member,

a drilling bit attached to one end of said rod member,

mechanical oscillator means for longitudinally vibrating said rod member and said bit at a resonant sonic frequency, and

torsional oscillator means attached to said rod member for torsionally oscillating said bit to and fro at a substantially lower frequency than that of the longitudinal vibration thereof whereby said torsional oscillator rotates said bit through at least a substantial fraction of a revolution in each rotational direction.

5. The device as recited in claim 4 wherein said torsional oscillator means comprises means for converting rotary motion into reciprocating motion.

6. An earth boring apparatus comprising a rod member,

a drilling bit attached to one end of said rod member,

means mounted on said rod member for longitudinally vibrating said rod member and said bit at a resonant sonic frequency,

motor means mounted on said rod member for driving said means for longitudinally vibrating said rod member,

means mounted on said rod member for converting rotary motion to reciprocal motion, said motion converting means being connected to said bit to provide to and fro oscillation thereof, and

step down gear train means mounted on said rod member for producing a stepped down rotary motion for driving said motion converting means to oscillate said bit at a substantially lower frequency than the longitudinal vibration thereof and through at least a substantial portion of a revolution in each rotational direction, said gear train means being rotatably driven by the output of said motor means.

7. The apparatus as recited in claim 6 wherein said means for longitudinally vibrating said rod member comprises an orbital mass oscillator rotatably driven by said motor means.

8. An earth boring apparatus comprising a rod member,

a drilling bit attached to one end of said rod member,

mechanical oscillator means mounted on said rod memher for longitudinally vibrating said rod member and said bit at a sonic frequency which is resonant with the effective longitudinal impedance thereof,

a torsion bar attached to the other end of said rod member,

mechanical oscillator means attached to said torsion bar for alternately applying opposite torsional couples to said torsion bar at a frequency different from the longitudinal vibration frequency of said rod member, and

cable means for suspensively supporting said torsion bar, said rod member and said bit,

whereby said bit is simultaneously vibrated longitudinally and torsionally twisted to and fro.

9. The apparatus as recited in claim 8, wherein said torsion bar is vibrated at a torsional resonant frequency.

10. An earth boring apparatus comprising a rod member,

a drilling bit attached to one end of said rod member,

means attached to said rod member for longitudinally vibrating said rod member and said bit at a sonic frequency which is resonant with the effective longitudinal impedance thereof,

a torsion bar attached to the other end of said rod member, and

means attached to said torsion bar for alternately applying opposite torsional couples to said torsion bar at a frequency different from the longitudinal vibration frequency of said rod member,

whereby said bit is simultaneously vibrated longitudinally and torsionally twisted to and fro.

11. The apparatus as recited in claim 10 wherein said means for longitudinally vibrating said rod member comprises an orbital mass oscillator and means for rotatably driving said oscillator.

12. The apparatus as recited in claim 11 wherein said means for applying torsional couples to said torsion bar comprises an orbital mass oscillator attached to the end of said torsion bar opposite the end thereof attached to said rod member and means for rotatably driving said oscillator.

13. A device for boring through earthen formations comprising a rod member,

a drilling bit attached to one end of said rod member,

mechanical oscillator means for longitudinally vibrating said rod member and said bit at a resonant sonic frequency, and

torsional oscillator means attached to said rod member for torsionally oscillating said bit to and fro at a different frequency than that of the longitudinal vibration thereof, said torsional oscillator means comprising a torsion stem and mechanical oscillator means for alternately applying opposite torsional forces to said stem.

14. The device as recited in claim 13 wherein said oscillator means applies a torsional force at a frequency which produces resonant to and fro vibration to the torsional system including said torsion stem, said rod me1nber and said bit.

References Cited by the Examiner UNITED STATES PATENTS 2,743,585 5/1956 Berthet et al. 746l 2,906,433 9/1959 Smith 56 X 2,911,192 11/1959 Boucher 175-56 2,975,846 3/1961 Bodine 175-55 X FOREIGN PATENTS 750,897 1/1945 Germany.

CHARLES E. OCONNELL, Primary Examiner.

R. E. FAVREAU, Assistant Examiner. 

1. A METHOD FOR EARTH BORING BY MEANS OF A DRILL BIT ATTACHED TO THE END OF A ROD MEMBER COMPRISING LONGITUDINALLY VIBRATING SAID ROD MEMBER AND SAID BIT AT A SONIC FREQUENCY, WHILE SAID ROD IS BEING LONGITUDINALLY VIBRATED TORSIONALLY OSCILLATING SAID BIT TO AND FRO AT A SUBSTANTIALLY LOWER FREQUENCY THAN THE LONGITUDINAL VIBRA- 